The present invention relates to a device that converts an electric current to pump pressure.
Positive displacement pumps and turbopumps are commonly used as fluid pumps. Japanese Laid-Open Patent Publication No. 2004-060640 discloses a diaphragm pump, which is a type of positive displacement pump, and Japanese Laid-Open Patent Publication No. 2009-011767 discloses a centrifugal pump, which is a type of turbopump.
A positive displacement pump requires a valve structure, or a shielding mechanism for a valve. When deteriorated, shielding mechanisms adversely affect the pump performance. Thus, the energy conversion efficiency of positive displacement pumps is lower than that of turbopumps. In contrast, turbopumps are superior in energy conversion efficiency and have a wide application range for the flow rate and discharge pressure. However, since a drive motor is attached to the outside of the pump, the overall size of a turbopump tends to be large. Further, a typical turbopump requires a shaft shielding mechanism for preventing liquid leakage (fluid leaks) about the shaft. To eliminate the shaft shield, a magnetic shaft may be used. However, a magnetic shaft requires an advanced type of magnetic control mechanism. Also, Japanese Laid-Open Patent Publication No. 2007-289911 does not disclose the details for an embodiment when the invention is used in a pump.